Chemical solution for detecting counterfeit paper currency

ABSTRACT

This invention relates to a solution for detecting counterfeit paper currency. The solution contains iodine at a concentration of from 0.005 to 3 grams/liter and one or more solvents selected from the groups consisting of: alcohols, ketones, polyalcohols, esters, ethers, or mixtures thereof of solvents belonging to the same group or to several groups of these solvents. The solvent, if miscible with water, contains distilled water in a ratio of from 99:1 to 1:99 parts by volume. If not miscible in water, the solvent is saturated with distilled water at a temperature of 20° C. The solution is preferably contained in ballpoint pens, fountain pens or other similar dispensers which are then used to countersign the paper currency. A counterfeit currency will cause a visible line to appear on the currency, in about one minute. However, in the case of genuine paper currency, the drawn line of solution does not change color and disappears completely from the countersigned currency.

TECHNICAL FIELD

This invention relates to a chemical solution for detecting counterfeitpaper currency.

BACKGROUND ART

Counterfeit of paper currency damages greatly not only the economy of aNation, adopting that particular paper currency, but also the Countrieswith which the Nation has import-export trade.

The development of the EEC and fall of the barriers within EasternEurope have increased the counterfeit business.

The U.S. Dollar is the most counterfeit currency, because of its widedistribution.

The possibility of using chemical solutions for detecting counterfeitpaper currency must be conducted without leaving any stain on thecountersigning banknote, according to the laws of the Countries whichforbid marking on any kind of paper currency.

Presently, there are available on the market some devices, usingchemical solutions, for detecting counterfeit paper currency.

In U.S. Pat. No. 5,603,163 a chemical solution is described, fordetecting counterfeit paper currency, that includes a high concentrationof iodine and iodides in an alkaline aqueous-alcoholic solutions and inthe presence of elevated hydrogen peroxide concentrations.

When said solution is used to draw a line on a banknote, this drawn linebecome brown and permanently persists on all countersigned banknotes,even if they are genuine: that is forbidden by all National laws.

Moreover, this cited patent describes the use of toxic or cancerogenicsolvents in the chemical solution, such as carbon disulfide, carbontetrachloride, and chloroform.

Document WO-A-84/03295 discloses an ink composition for use in ink jetprinting comprising an aqueous solution of a water soluble dye, a starchstaining combination and a viscosity enhancer.

The most important features of this ink are:

increased optical density of a printed dot, achieved by the sum oftinctorial effects of dye on cellulose and KI+I₂ starch sizing reaction;

omission of bacteriocide, due to relatively high iodine concentration;

increased water and light permanency.

This ink stains or marks a starch content paper such as xerographicpapers, bond papers, cotton filled papers, all of which have a highstarch content.

Ink solution always includes a commercial liquid dye together with theKI₃ +I₂ radical ion combination that reacts with the starch in the paperto produce an organic complex that has a very deep blue colour.

This ink solution is used to provide a significant increase in theoptical density of every printing made with the ink itself in comparisonwith the standard ink.

When said ink solution is used to draw a line on a banknote this drawnline will lie permanently on the countersigned banknotes, due to thehigh concentration of KI₃ and the low volatility of said ink solution.

The described solution and other known solutions have not resolved in afully effective way the problems connected with the safe detection ofcounterfeit paper currencies.

DISCLOSURE OF THE INVENTION

The object of the present invention is to propose a chemical solutionthat can be contained in a suitable dispenser such as a fountain-pen orball point pen or felt-tip pen or other devices and that is able todetect counterfeit paper currency by its application on the latter, i.e.by drawing a line on the paper currency.

In fact, in the case of a genuine paper currency the drawn line willassume no color, on the contrary, in the case of counterfeit papercurrency, the drawn line will assume a color, whose tonality will varyfrom lilac to lilac-violet or to deep blue or to havana yellow.

A further object of the invention is to propose a solution that can bespread (for example like a line) on the paper currency and afterreaction with this latter it leaves no colored trace on the drawngenuine paper currency, because this solution contains a particularconcentration of iodine in a suitable organic solvent distilled watermixture.

This represents a safe method to detect counterfeit paper currency,because the iodine contained in the chemical solution reacts with thecompounds which are normally present in the paper of counterfeitcurrency, such as amylose, amylodextrin, starch, or compounds derivedfrom hydrolysis of cellulose, i.e. dextrins of different molecularweights, or organic polymers added during the paper manufacturingprocess.

On the other hand, in the genuine paper currency the iodine does notfind these substances and it does not react during or after theapplication of the chemical solution onto the paper currency.

BEST MODE OF CARRYING OUT THE INVENTION

The chemical solution is obtained by dissolving metallic iodine in asolvent saturated with distilled water at a temperature of 20° C. ormixed with distilled water in the volumetric ratio ranging from 1:99 to99:1.

The solvent could be a single compound or a mixture of compoundsbelonging to the same chemical group or to different chemical groups.

The single compound could be one of the following alcohols: methyl,ethyl, propyl, isopropyl, butyl, isobutyl; one of the following ketones:acetone, ethylketone, methylethylketone, methylprophylketone,prophylketone, diethylketone; one of the following polyalcohols:glycerol, ethylene glycol, propylene glycol, diethylene glycol, hexyleneglycol, sorbitol, polyethylene glycols, and 1,2 propylene glycol; one ofthe following esters of formic, acetic, propionic, lactic acids with theaforementioned alcohols or polyalcohols; one of the following ethers ofmethyl, ethyl, propyl, butyl alcohols or polyalcohols.

The mixtures of compounds are mixtures in a suitable proportion ofsingle compounds belonging to the same group i.e., alcohol, ketone,polyalcohol, ester, or ether group or of different compounds belongingto the different mentioned groups.

The solvent is added with distilled water at the temperature of 20° C.in the volumetric ratio ranging from 1:99 to 99:1 in the case of thesolvents which are completely soluble in water. If the solvent is notcompletely soluble in water, the distilled water is added to the solventtill its saturation with water is achieved.

The metallic iodine is dissolved in one of the aforementioned solvents,mixed with distilled water in an amber-coloured flask, under a vacuumhood, in the absence of sunlight, at a temperature of 20° C., bymagnetic stirring in an inert atmosphere (i.e. nitrogen or carbondioxide).

Then the solution of iodine is diluted with the chosen solventpreviously mixed with water to obtain the desired concentration ofiodine, that is, ranging from 0.005 to 3 grams/liter of the solvent.

The preferred chemical solution to detect counterfeit paper currencyuses the following solvent: 2-propanol-diethylene glycol-ethyleneglycol-distilled water with relative volumetric ratio of 30:10:14:46added with 2.0 grams of iodine per liter of the above solvent.

A further chemical solution uses the following solvent:propanol-diethylene glycol-ethylene glycol-distilled water with therelative volumetric ratio of 30:10:14:46. This solvent is added with 2.0grams of iodine per liter of the same solvent.

In order that the present invention may be more fully understood, thefollowing examples are set forth for illustrative, but in no wayrestrictive, purposes.

EXAMPLE 1

In a one liter volumetric amber-coloured flask, 0.95 grams of metalliciodine were dissolved with 900 ml of methyl acetate to which were added,under moderate stirring at 20° C., 180 m of distilled water, obtainingtwo liquid phases.

Then the mixture was transferred into a separation funnel obtaining anupper phase of methyl acetate saturated with water, and a bottom phaseconstituted by water saturated with methylacetate.

To the upper phase was added with 18 ml of 2,3 propylene glycol. Thiswas poured into a dropper or similar dispensing device, for example afelt tip pen: this was the solution used to detect the counterfeit papercurrency.

Thus, using a felt tip pen containing the above solution, a line of 2 cmin length was drawn on a genuine Italian bank-notes of100.000-50.000-10.000-5.000-2.000-1.000 Italian Lire; on the genuinebank-notes of Great Britain, i.e. 10-20-50 Pounds; and on the sheets ofthe letter paper, of the drawing paper, of the proofing paper and of thephotocopy paper.

After 30 seconds from the application of the solution on the genuinebank-notes, none of the tested currency showed any colored lines.

On the contrary, the drawn lines on the other kinds of paper becamecolored with a tonality ranging from lilac to violet to deep blue.

EXAMPLE 2

1.70 grams of iodine were introduced into an amber-coloured flask anddissolved in one liter of a solution which contained: 400 ml ofisopropyl alcohol, 200 ml of ethylene glycol and 400 ml of distilledwater.

The solution was put inside a felt tip pen which was used to draw linesof 2 cm in length on genuine 10-50-100 U.S. Dollars, on genuine10-50-100 German Marks and on the common sheets of letter, proofing,drawing and photocopy papers.

15 second after the application of the solution, no coloured linesappeared on all the genuine paper currency, while the lines drawn on theother sheets of paper were colored lilac, or violet, or bluish-violet,or bluish ashen grey.

EXAMPLE 3

In a two liter amber-coloured flask, under stirring at a temperature of15° C. and under a fume exhaust hood, 4.6 grams of iodine were dissolvedwith a solvent mixture containing acetone, propyl alcohol, water in arelative volumetric ratio of 30:45:25.

The above solution was dispensed by a felt tip pen to draw a line ofabout 2 cm in length on each of the following bank-notes: 100 GermanMarks, 10 British pounds, 10 Grecian drachms, all of them obtained froma local bank and thus considered genuine. A line was drawn also onseveral sheets of paper used for different services.

The drawn lines gave no one color on the tested genuine bank-notes; onthe contrary, the lines on the sheets of papers immediately gave coloursof different tonality, such as lilac-violet or dark bluish or bluishashen dark grey, according to the different chemical nature of the papersheets.

EXAMPLE 4

By stirring at 15° C. and under the fume exhaust hood, in a 2 literamber-coloured flask, 4 grams of iodine were dissolved with a solventmixture, which contains 2-propanol-diethylene glycol-ethyleneglycol-distilled water with relative volumetric ratio of 30:10:14:46.

This solution was dispensed by a felt tip pen to draw a 2 cm line ongenuine bank-notes of 2, 5, 10, 50, 100 Canadian Dollars, and also ondifferent paper sheets.

The drawn lines did not assume any coloration on the tested genuinebank-notes, while the lines on the other paper sheets immediatelyappeared colored with different tonality, such as lilac-violet or darkbluish or bluish ashen dark grey, according to the different chemicalnature of each paper sheet.

INDUSTRIAL APPLICABILITY

The described chemical solution could be easily contained inside asuitable dispensing device such as fountain-pen or ball point pen orfelt-tip pen.

Moreover, this chemical solution to detect counterfeit paper currency issimply used by drawing a line on the paper currency to be tested. Atmaximum in about one minute, it is possible to recognise genuinecurrency because the drawn line disappears completely from the genuinecurrency. Otherwise for counterfeit currency it assumes a color, whosetonality will vary from lilac to lilac-violet or to deep blue or tohavana yellow.

The peculiarity of this chemical solution is that it leaves no trace onany genuine paper currency so that it is compatible with to the laws ofevery Nations having laws on that matter.

I claim:
 1. A chemical solution to detect counterfeit paper currencycomprising metallic iodine of 99.9% purity, and a solvent selected fromthe groups consisting of alcohols, polyalcohols, ketones, esters of thealcohols or the polyalcohols, with formic, acetic, propionic or lacticacid, ethers of methyl, ethyl, propyl, or butyl alcohols, or of thepolyalcohols, mixtures of solvents selected from one or more of thegroups, the selected solvent being not completely soluble in water andbeing mixed, at a temperature of 20° C. with distilled water in avolumetric ratio ranging from 99 percent to the volume of saturation ofthe selected solvent with the distilled water, at the temperature of 20°C., the metallic iodine dissolved at a temperature of 20° C., in theselected solvent.
 2. A chemical solution according to claim 1, whereinsaid selected solution contains metallic iodine at a concentrationvarying from 0.005 to 3.0 grams per liter.
 3. A chemical solutionaccording to claim 1, wherein the alcohols are selected from the groupconsisting of methyl, ethyl, propyl, isopropyl, butyl, and isobutylalcohols, and mixtures thereof.
 4. A chemical solution according toclaim 1, wherein said polyalcohols are selected from the groupconsisting of glycerol, ethylene glycol, propylene glycol, diethyleneglycol, hexylene glycol, sorbitol, polyethylene glycols and 1,2propylene glycol, and mixtures thereof.
 5. A chemical solution accordingclaim 1 wherein said esters are formic, acetic, propionic, or lacticesters of the alcohols selected from the group consisting of methyl,ethyl, propyl, isopropyl, butyl, isobutyl alcohols and mixtures thereof,and of the polyalcohols selected from the group consisting of glycerol,ethylene glycol, propylene glycol, diethylene glycol, hexylene glycol,sorbitol, polyethylene glycols, 1,2 propylene glycol and mixturesthereof.
 6. A chemical solution according to claim 1 wherein saidketones are selected from the group consisting of acetone, methyl ethylketone, diethyl ketone, propyl ketone, isopropyl ketone and mixturesthereof.
 7. A chemical solution according to claim 1 wherein said ethersare of alcohols selected from the group consisting of methyl, ethyl,propyl, isopropyl, butyl, and isobutyl alcohols, and mixtures thereofand of polyalcohols selected from the group consisting of glycerol,ethylene glycol, propylene glycol, diethylene glycol, hexylene glycol,sorbitol, 1,2 propylene glycol and mixtures thereof.
 8. A chemicalsolution according to claim 1 wherein the selected solvent withdistilled water has the following formulation:2-propanol-diethyleneglycol-ethylene glycol-distilled water, the relative volumetric ratiobeing 30:10:14:46; one liter of said solvent used per 2.0 grams of saidmetallic iodine.
 9. A chemical solution according to claim 1 wherein thesaid solvent with distilled water has the followingformulation:propanol-diethylene glycol-ethylene glycol-distilled waterwith the relative volumetric ratio being 30:10:14:46; one liter of saidsolvent used per 2.0 grams of said metallic iodine.
 10. A chemicalsolution to detect counterfeit paper currency comprising metallic iodineof 99.9 percent purity and a solvent selected from the groups consistingof alcohols, polyalcohols, ketones, esters of the alcohols or thepolyalcohols with formic, acetic, propionic or lactic acid, ethers ofmethyl, ethyl, propyl, butyl alcohols or of the polyalcohols, andmixtures of solvents selected from one or more of the groups, theselected solvent being mixed at a temperature of 20° C. with distilledwater in a volumetric ratio variable from 99 percent of water to thevolume of saturation of the selected solvent with distilled water, atthe temperature 20° C. the metallic iodine dissolved at a temperature of20° C. in the solvent, wherein said esters are formic, acetic,propionic, or lactic esters of the alcohols selected from the groupconsisting of methyl, ethyl, propyl, isopropyl, butyl, isobutyl alcoholsand mixtures thereof, and of the polyalcohols selected from the groupconsisting of glycerol, ethylene glycol, propylene glycol, diethyleneglycol, hexylene glycol, sorbitol, polyethylene glycols and 1,2propylene glycol and mixtures thereof.
 11. A chemical solution accordingto claim 10 wherein said solution contains metallic iodine at aconcentration of from 0.005 to 3.0 grams/liter.
 12. A chemical solutionaccording to claim 10 wherein said selected solvent is completelysoluble in water and contains distilled water in a volumetric ratioranging from 1 percent to 99 percent of the mixture, at a temperature of20° C.
 13. A chemical solution to detect counterfeit paper currencycomprising metallic iodine of 99.9 percent purity and a solvent selectedfrom the groups consisting of alcohols, polyalcohols, ketones, esters ofthe alcohols or the polyalcohols with formic, acetic, propionic orlactic acid, ethers of methyl, ethyl, propyl, butyl alcohols or of thepolyalcohols, and mixtures of solvents selected from one or more of thegroups, the selected solvent being mixed at a temperature of 20° C. withdistilled water in a volumetric ratio variable from 99 percent of waterto the volume of saturation of the selected solvent with distilledwater, at the temperature of 20° C., the metallic iodine dissolved at atemperature of 20° C. in the solvent, said ketones selected from thegroup consisting of acetone, methyl ketone, ethyl ketone, diethylketone, propyl ketone and isopropyl ketone.
 14. A chemical solutionaccording to claim 13 wherein said solution contains metallic iodine ata concentration of from 0.005 to 3.0 grams/liter.
 15. A chemicalsolution according to claim 13 wherein said selected solvent iscompletely soluble in water and contains distilled water in a volumetricratio ranging from 1 percent to 99 percent of the mixture, at atemperature of 20° C.
 16. A chemical solution to detect counterfeitpaper currency comprising metallic iodine of 99.9 percent purity and asolvent selected from the groups consisting of alcohols, polyalcohols,ketones, esters of the alcohols or the polyalcohols with formic, acetic,propionic or lactic acid, ethers of methyl, ethyl, propyl, butylalcohols or of the polyalcohols, and mixtures of solvents selected fromone or more of the groups, the selected solvent being mixed at atemperature of 20° C. with distilled water in a volumetric ratiovariable from 99 percent of water to the volume of saturation of theselected solvent with distilled water, at the temperature of 20° C., themetallic iodine dissolved at a temperature of 20° C. in the solvent,wherein said ethers are of alcohols selected from the group consistingof methyl, ethyl, propyl, isopropyl, butyl, isobutyl alcohols, and ofpolyalcohols selected from the group consisting of glycerol, ethyleneglycol, propylene glycol, diethylene glycol, hexylene glycol, sorbitol,and 1,2 propylene glycol and mixtures thereof.
 17. A chemical solutionaccording to claim 16 wherein said solution contains metallic iodine ata concentration of from 0.005 to 3.0 grams/liter.
 18. A chemicalsolution according to claim 16 wherein said selected solvent iscompletely soluble in water and contains distilled water in a volumetricratio ranging from 1 percent to 99 percent of the mixture, at atemperature of 20° C.
 19. A chemical solution to detect counterfeitpaper currency comprising metallic iodine of 99.9 percent purity and asolvent selected from the groups consisting of alcohols, polyalcohols,ketones, esters of the alcohols or the polyalcohols with formic, acetic,propionic or lactic acid, ethers of methyl, ethyl, propyl, butylalcohols or of the polyalcohols, and mixtures of solvents selected fromone or more of the groups, the selected solvent being mixed at atemperature of 20° C. with distilled water in a volumetric ratiovariable from 99 percent of water to the volume of saturation of theselected solvent with distilled water, at the temperature of 20° C., themetallic iodine dissolved at a temperature of 20° C. in the solvent,wherein the selected solvent with distilled water has the followingformulation:2-propanol-diethylene glycol-ethylene glycol-distilledwater, the relative volumetric ratio being 30:10:14:46; one liter ofsaid solution used per 2.0 grams of said metallic iodine.
 20. A chemicalsolution to detect counterfeit paper currency comprising metallic iodineof 99.9 percent purity and a solvent selected from the groups consistingof alcohols, polyalcohols, ketones, esters of the alcohols or thepolyalcohols with formic, acetic, propionic or lactic acid, ethers ofmethyl ethyl, propyl, butyl alcohols or of the polyalcohols, andmixtures of solvents selected from one or more of the groups, theselected solvent being mixed at a temperature of 20° C. with distilledwater in a volumetric ratio variable from 99 percent of water to thevolume of saturation of the selected solvent with distilled water, atthe temperature of 20° C., the metallic iodine dissolved at atemperature of 20° C. in the solvent, wherein the selected solvent withdistilled water has the following formulation:propanol-diethyleneglycol-ethylene glycol-distilled water, the relative volumetric ratiobeing 30:10:14:46; one liter of said solution used per 2.0 grams of saidmetallic iodine.
 21. A method for detecting counterfeit currencycomprising the steps of:providing a paper currency to be tested,providing a chemical solution for detecting counterfeit paper currencycomprising metallic iodine of 99.9 percent purity dissolved in a solventselected from the groups consisting of alcohols, polyalcohols, ketones,esters of said alcohols and of said polyalcohols with formic, acetic,propionic or lactic acid ethers of methyl, ethyl, propyl, and butylalcohols, ethers of said polyalcohols and mixtures of solvents selectedfrom one or more of the groups, said selected solvent being added todistilled water in a volumetric ratio ranging from 99 percent to thevolume of saturation of the selected solvent with distilled water at atemperature of 20° C. applying said chemical solution to an area of thepaper currency; and determining whether a color change takes place, thechemical solution leaving a visible mark only on counterfeit currency,leaving no mark on genuine currency.
 22. A method for producing achemical solution to detect counterfeit paper currencycomprising:providing metallic iodine of 99.9 percent purity; dissolvingthe metallic iodine in a solvent selected from the groups consisting ofalcohols, polyalcohols, ketones, esters of said alcohols and of saidpolyalcohols, with formic or acetic or propionic or lactic acid, ethersof methyl, ethyl, propyl, and butyl alcohols or of said polyalcohols,and mixtures of solvents selected from one or more of the groups; mixingthe selected solvent at a temperature of 20° C. with distilled water ina volumetric ratio ranging from 1 percent to 99 percent or to the volumeof saturation of the selected solvent with distilled water at atemperature of 20° C.; and, dissolving the metallic iodine at aconcentration of from 0.005 to 3.0 grams/liter in the selected solventwith distilled water at a temperature of 20° C. in an amber color flask,in the absence of sunlight, with stirring, in a non-oxidant atmosphere.23. A chemical solution to detect counterfeit paper currency consistingessentially of metallic iodine of 99.9 percent purity and a solventselected from the groups consisting of alcohols, polyalcohols, ketones,esters of said alcohols, or of said polyalcohols, with formic, acetic,propionic or lactic acid, ethers of methyl, ethyl, propyl, or butylalcohols or of said polyalcohols, and mixtures of solvents selected fromone or more of the groups, said solvent containing distilled water in avolumetric ratio variable from 99 percent of water to 1 percent or tothe volume of saturation of the selected solvent with distilled water,the metallic iodine present at from 0.005 to 3.0 grams/liter.